Strainer



J, E. LODGE WINE}! May 9, 1950 Filed Jan. 7, 1948 E m G T D m 0 at v w J 2 I l- E 2 v mu R R ll 3 &\8 R 8 Q L g l/Zr llll 2 M m u on f Mn 3 3 .Il \R. Q N\ 3 a..

ATTORNEY 1950 I J. E. Loos: 2,507,311

. S'TRAINER Filed Jan 7, 194a INVENTOR .16. L 06E A T TORNEY 4 Sheets-Sheet 2 1 y ,1950 J. E. LODGE 2,501,3

STRAINER Filed Jan. 7, 1948 4 Sheets-Sheet 3 n v n k x Q g Q '2 v a: a o A Q o a FIG 4 a k L q N n r V 8 Q Q to Q Q Q N o q R Q n m/10R .15 LODGE a Br V ATTORNEY Patented May 9, 1950 STRAINER Joseph E. Lodge, Baltimore, Md., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application January 7, 1948, Serial No. 899

8 Claims. 1

This invention relates to strainers, and more particularly to apparatus for effecting a rapid change of straining elements used in such apparatus.

Extrudable materials, such as rubber compounds, or the like, are used extensively with extruding machines which apply an insulating cover or jacket of such material around an advancing core. Such compounds usually consist of a number of ingredients which are mixed together in a suitable mixing machine, such as a machine commonly referred as a Banbury mixer." Frequently, the mixed compound contains certain unmixed lumps of the various ingredients or lumps of foreign matter, which must be removed or strained from the compound before the material is supplied to the extruding machines.

Various types of strainers are employed to strain the compound immediately after it has been discharged from the mixing machine. In

- general, they consist of a cylinder having a rotating stock screw therein which forces the mixed compound through a screen suitably positioned across the end of the cylinder. When the screen becomes clogged up with foreign matter and lumps of unmixed material, it is necessary to either clean the screen or replace it with another screen. In either case the screen changing operation on the present type of straining apparatus requires a substantial amount of manual labor and results in a substantial loss of operating time for the straining machine. Since the extruding apparatus requires a continuous supply of compound, the shutdown periods of the straining apparatus must be as short as possible.

An object of the invention is to provide new and improved strainers.

Another object of the invention is to provide new and improved apparatus for effecting a rapid change of straining elements in strainers.

An apparatus embodying certain features of the invention comprises a strainer head arranged to be mounted on the end of a cylinder having a stock screw rotatably mounted therein for conveying a compound to be strained into the straining head, a plurality of belt-like strainer screens slidably positioned across the opening of the strainer head, a plurality of perforated plates slidably positioned across the opening of the strainer head contiguous to the screens to support them as the stock screw forces the compound through the screens and means for holding the perforated plates in position as the compound is forced therethrough.

A complete understanding of the invention will be had from the following detailed description of a specific embodiment, when read in conjunction with the appended drawings, in which:

Fig. 1 is a plan view of a strainer head and an associated screen changing apparatus embodying specific features of the invention;

Fig. 2 is an end view of the strainer head shown in Fig. 1;

portion ll having an annular flange l2 provided on one end thereof and a rectangular flange I3 provided on the other end thereof. The flange P2 of the head I0 is arranged to be bolted to the end of a-tuber cylinder, a portion of which is indicated by the numeral ll, which cylinder is provided with a stock screw l5 arranged to be rotated in a bore I6 provided in the cylinder. The head In is provided with a bore l'l equal in diameter tothe bore IE to receive the end of the stock screw l5 which extends a substantial distance into the head l0.

The bore I! (Fig. 6) flares outwardly-at the opposite end of the head ID to communicate with a rectangular opening l8 embraced by the flange I3. A shoulder is is provided on each horizontal side of the flange l3 which is flush with the face of the vertical legs of the flange. A hardened steel strip 20 is pressed into grooves provided in the shoulders l9l9 and the vertical legs of the flange l3 so that one end thereof projects slightly beyond the surface of the shoulders and the vertical legs of the flange. An elongated plate 2| is secured along the upper horizontal portion of the flange and an elongated plate 22 is secured along lower horizontal portion of the flange l3. which plates coact with their respective adjacent shoulder I9 to form horizontal grooves 23-23 in the opening it of the flange i3.

A channel-shaped support 24 is formed integrally with the head I II on the right side of the flange l3 (Fig. 2) and is provided with a shoulder 25 in the upper leg thereof and a groove 26 in the lower leg thereof (Fig. 2) which communicate with grooves 23-23 provided in the horizontal sides of the flange l3. A rectangular slot 21 is provided at the end of the support 24 (Fig. l) to provide an opening through which screens 30, 3| and 32 are advanced from their respective rolls 33, 34 and 35 to the shoulder 25 and the groove 26. A roller 36 (Fig. 2) is rotatably mounted in a suitable manner within the slot 2'! and between the horizontal legs of the channel-shaped member 24 to guide the screens 30, 3| and 32 from their respective rolls into the grooves provided in the support 24 and the head "I.

The screens 30, 3| and'32 are drawn from their respective rolls and pass through the slot 21 into the shoulder 25 and the groove 26 and thence into the grooves 23-23 provided in the head II. The width of the screens 30, 3| and 32 are such that they are slidable in their own plane into the grooves 23-23, and when positioned therein they overlap the rectangular opening l3. The rolls 33, 34 and are rotatable about shafts 31-31 mounted vertically between supports 33-33 (Figs. 1 and 3) spacedly mounted on the support 24 to suit the width of the screens 30, 3| and 32. It will be noted from Fig. 6 that screen 30 is positioned against the end of the strips 20-20 positioned around the flange l3 and adjacent to the end of the stock screw l5. that the screen 3| is positioned behind the screen 33 and that the screen 32 is positioned behind the screen 3| when the screens are drawn across the opening I! of the head II. The head I6 is designed so as to be or such length that only a relatively narrow clearance is provided between the end of the screw |5 and the screen 35.

A channel-shaped support 33 is formed integrally with the head ll on the left side of the flange l3 and is provided with a shoulder 46 in the upper leg thereof and a groove 4| in the lower leg thereof which are aligned with and communicate with the grooves 23-23 provided in the horizontal sides of the opening II. A rectangular slot 42 is provided in the back of the support 33 to allow the screens extending beyond the opening I! to pass from the support 39 to a takeup shaft 44 rotatably mounted between brackets -45 spacedly mounted on the rear of the channel-shaped member 33 to suit the width of the screens. A roller 46 is rotatably mounted in a suitable manner within the opening 42 and between the horizontal legs of the support 39 to guide the screens from the shoulder 40 and the groove 4| to the takeup shaft 04. A suitable type of torque motor 41 is coupled directly to the lower end of the shaft 44 and arranged to be energized from a suitable source of electric potential in order to rotate the shaft 44 and take up the screens 36, 3| and 32 when desired.

A pair of perforated plates -50 are slidably positioned in tandem across the opening 13 by 1 means of flanges 5l-5l provided at the top and bottom edges of the plates which engage a portion of the grooves 23-23 provided in the head II. The plates -53 are identical in size and shape, and each plate is of such width that it covers one-half of the opening II. To assemble the plates 53-56 in position across the opening l3 of the head I. so that they occupy the positions designated A and B on the drawings, one of the plates 53-53 is positioned in the support 24 so that the bottom flange 5| ot the Plate engages the groove 26 (Fig. 2) while the upper edge of the plate rests against the shoulder 25.

When the plate is in this position it may be slid laterally along the groove 26 and against the shoulder 25 until the'fianges 5|-5| of the plate enter the grooves 23-23 of the head l0. When the plate reaches the position B, shown on the drawing, a. second plate 50 is positioned in the support 24 in the same manner described for the first plate and slid laterally to the left until it enters the grooves 23-23 and assumes position B. In sliding the second plate 50 into the B position across the opening l8, the first plate is pushed across the opening and subsequently will assume the A position, across the opening. In this way, the plates 50-50 completely cover the opening l8 and completely back up the unsupported area of the screens 30. 3| and 32 positioned across the opening.

The perforated plates 50-50 have been described as being a pair of plates because as such they facilitate easy assembly across the opening l3. It is believed to be apparent that the perforated plates 50-50 may be combined into a single perforated plate and the support 24 lengthened to permit such a single plate to be positioned therein so that it may be moved laterally to the left to its operating position across the opening l3. By using two half size plates 50-50 the length of the support 24 may be materially shortened which may be advisable where itis necessary to keep the size of the strainer head to a minimum.

Continuous rotation of the stock screw l5 conveys an extrudable material 52 from a, suitable supply hopper (not shown) through the head N to the screens and the perforated plates. A considerable pressure is built up in the mass of material 52 directly adjacent to the screens as the extrudable material 52 is forced through the screens. Due to the high pressure required to force the extrudable material 52 through the screens 30, 3| and 32, it is necessary to provide a suitable supporting means for the plates 50-50. The flanges 5| -5| provided on the top and bottom sides of the plates 50-50 are not intended to hold the plates against the high pressure devel+ oped in the material as the material is forced through the screens but are provided merely as means for guiding the plates as they are slid into position across the opening l8.

The means for holding the plates against the pressure developed in the extrudable material 52 disposed in the bore ll of the head |0 comprises a central yoke 53 and yokes 54-54 which are suspended vertically across the opening M. The central yoke 53 is identical in size and shape to the yokes 54-54, except for a pad 55 provided on the inner edge thereof for the purpose of overlappin the central joint between the plates 50-50. The yokes are arranged to be movable longitudinally of the head In to simultaneously engage the plates 50-50 and press the overlapping portions of the screens tightly against the end of the strips 20-20 positioned in the grooves 23-23 or simultaneously disengage the plates so that they are freely slidable in the grooves 23-23 in a manner hereinafter to be described.

A plurality of lugs 56-56 (Figs. 1, 2 and 6) are equally spaced along the top side of the rectangular flange I3. The lugs 56-56 are formed integrally with the flange |3 in order to obtain maximum strength between them and the head II. A splined shaft 51 is rotatably mounted in each of the lugs 56-56 in the following manner: Each of the lugs 56-56 is provided with a bore 53 (Fig. 6) to receive a hardened steel bushing 50, which bushing is equal in length to the width of the particular lug in which the bushing is assembled. A splined sleeve 6| is positioned on that portion of the shaft 61 embraced by the bushing and is of substantially thesame length as the bushing. A needle bearing 62 is positioned in the annular clearance formed between the splined sleeve 6| fitted in the shaft 51 and the bushing 60 fitted in the bore 56. Such an assembly is provided in each of the lugs 56-56, whereby the shaft 51 is freely rotatable in each of the lugs.

A plurality of lugs 63-63 are ormed integrally with and equally spaced along the lower surface of the rectangular flange i3 of the head l0. The lugs 63-63 positioned along the lower surface of the flange l3 are of the same thickness as and vertically aligned with the lugs 56-56, whereby the openings between the lugs are vertically aligned with each other. A splined shaft 64 is rotatably mounted in each of the lugs 63-63 in exactly the same manner as that in which the shaft 51 is rotatably mounted on the lugs 56-56.

One end of a toggle link 65 is slidably positioned in each of the openings between the lugs 56-56 and 63-63 and is mounted on the splined shafts 51 and 64 in the following manner: The end of each of the links 65-65 positioned between the lugs is provided with a bore 66 in which is pressed a hardened bushing 61. A splined cam 10 is positioned over each portion of the shafts 51 and 64 which is embraced by the end of a link 65. A needle bearing 1i is positioned in the annular clearance formed between the splined cam 10 an the bushing 61.

Each of the toggle links 65-65 is provided with a forked end 12 arranged to slidably receive the ends of the central yoke 53 and yokes 54-54,

and is provided with a bore 13 which is aligned with a bore 14 provided in-each end of the yokes so that a pin 15 may be passed therethrough to connect the ends of the yokes to the toggle links. A plate 16 is positioned between the yokes 53 and 54-54 to prevent the material through the screens and the plates from dropping on the forked ends 12-12 of the links 65-65 and the pin 15, whereby the material is prevented from collecting on the forked ends of the links and the pin 15 and prevent free movement of the links with respect to the yokes.

When the shafts 51 and 64 are rotated through one revolution, each of the toggle links mounted on the shafts will be urged alternately to the right, and then to the left, assuming that the shafts 51 and 64 were initially in the position shown in Fig. 6 of the drawings. Each associated pair of toggle links 65-65 moves its re-' spective yoke away from the plates 50-50 or toward the plates 50-50 depending upon the position of the cams 10-10 on the shafts 51 and 64. When the cams 10-10 are in the position shown in Fig. 6, the toggle links have drawn their respective yokes against the plates 50-50 which in turn press the overlapping portions of the screens 30, 3i and 32 tightly against the Strips -20 positioned in the grooves 23-23 and the vertical legs of the flange i3. The narrow edges of the strips cause the plates to exert a high unit pressure against the screens on the strips and press the screens together so as to close the interstices between the screens and seal .the opening l8 against leakage of the material 52. This is the operating position of the yokes and the toggle links and the screw i5 may then be operated to force the extrudable material 52 through the screens and through the perforated plates 50-50.

The yokes 53 and 54-54 serve to hold the 6 plates 60-60 in position against the high pressure developed in the extrudable material 52 as it is forced through the screens by the stock screw. The width of the plate 22 secured along the lower horizontal portion of the flange I3 is of such width that it engages the bottom, of the yokes throughout the total outward movement imparted to the yokes by the splined cams positioned on the shafts 51 and 64. By this arrangement the yokes always are aligned within the edge of the plates 2| and 22 and merely slide in and out of the opening l6.

Theshafts 51 and 64 which carry the splined cams 10-10 which actuate the links 65-65, one of which is shown in Fig. 6, are arranged to be rotated so as to cause the yokes connected to the links to engage or disengage the plates in a manner hereinafter to be described. A worm gear 60 is keyed on the left end of each of the shafts 51 and 64. A set collar 6| is positioned on the right end of each of the shafts 51 and 64 to prevent lateral movement of the shafts within the lugs 56-56 and 63-63. A shaft 62 is rotatably mounted in suitable bearings 63-63 (Fig. 4) mounted on the support 39 and has a worm 64 positioned on each end thereof so as to mesh with the worm gears 60-60 keyed on the shafts 51 and 64. In this way the shafts 51 and 64 are driven in unison when the shaft 62 is rotated. A worm gear is keyed 0n the upper end of the shaft 62 and meshes with a w rm 66 driven by a suitable motor 61 suitably mounted on the head l0.

When the motor 61 is connected to a suitable source of potential, it rotates the worm 66 which in turn drives the shaft 62 through the worm gear 65- at a predetermined rate of speed. The shaft 62 in turn drives the shafts 51 and 64 in the same direction and at a predetermined rate of speed through the worm gears 60-60 and worms 64-64. Having \the cams 10-10 positioned, as shown in Fig. '6. the shafts 51 and 64 need be rotated only one-half revolution to disengage the ends of the yokes from the perforated plates 50-50, and a second one-half revolution of the shafts will bring the yokes back into engagement with the plates 50-50. Due to this arrangement, the motor 61 need not be a reversible type of motor, as one complete revolution of the shafts 51 and. 64 will restore the yokes 53 and 54-54 to their normal operating position against. the plates 50-50.

It is desirable to incorporate in the control circuit of the motor 61 suitable electrical switching apparatus for terminating the operation of the motor when the yokes have been completely disengaged from the plates 50-50 and again when the yokes have been restored to their normal operating position against the plates 50-50. Only a relatively simple control circuit including suitable limit switches operated by the shafts 51 and 64 need be employed for accomplishing this cycle of operation of the motor 81, and, therefore, a description of a particular circuit that could be employed is unnecessary here since it forms no part of the invention.

While it has been pointed out hereinabove that the screens 30, 3i'and 32 and the-plates 50-60 may be assembled in position across the opening I6 of the head 10 manually, it is only possible to perform the assembly manually when there is no 7 the material 52 is embedded in the mesh of the screens and the perforations of the plates 50-50.

Continued operation of the stock screw causes the screens to become clogged with foreign matter and agglomerates, whereupon it becomes necessary to change the screens. Under these conditions the screens cannot'be disengaged manually from the extrudable material 52 which has become embedded into the screens, and it is necessary to provide means for moving the plates and the screens as a unit across the opening is so as to place thereacross fresh areas of the screens 30, 3| and 32 and another pair of plates 50-50.

The apparatus employed for changing the screens and the plates consists of a hydraulic cylinder, indicated generally by the numeral 90 (Figs. 1 and 5) which comprises an annular head 3| formed integrally on the end of the support 24, a cylinder 32 clamped between the head 3| and an annular head 33 by a plurality of bolts 94-94.

A piston 35 is positioned within the cylinder 92 and is provided with a piston rod 95 which extends through a central bore provided in the head II and has the free end thereof secured to a rectangular ram 51 arranged to slideagainst the shoulder 25 and in the groove 25 provided in the support 24. The hydraulic cylinder 30 is so arranged that when the piston 35 is positioned at the right end of the cylinder it draws the ram 01 to the right so that there is suillcient clearance between the ram and the end of the plate 50 cccupying position B across the opening I3 to permit another perforated plate like I the plates 53-53 to be inserted therebetween.

Suitable pipes I33 and III are secured to the heads 3| and 33, respectively, for admitting or discharging a hydraulic fluid into or from the hydraulic cylinder 33. The pipes I and I0! may be connected in a suitable manner to a conventional four-way control calve I32 arranged to admit the hydraulic fluid to the proper end of the cylinder when it is desired to cause a particular movement of the ram 31. A suitable conveyer indicated generally by the numeral 05 is positioned so as to pass beneath the plates IS-l5 so as to catch the material emerging from the strainer head I. and convey it to the particular apparatus in which the material is to be further used or The ram could also be actuated as described by means of an elongated screw and its associated driving unit, a rack and gear arrangement or other suitable means.

Operation Let it be assumed that the straining head I0 is to be set up to strain a particular compound such a the compound 52, and that no compound is in the bore ll of the head II. The type of compound to be strained determines the mesh of screens to be used in the straining operation. The selected rolls of the straining screens having the proper mesh, such as the rolls 33, 34 and 35, are

mounted on the shafts 31-31 carried by the sup-- pound, the pressure developed in the material 52 as it is strained is against this screen. Therefore, the screen 32, which is a substantially coarser mesh screen than the screen 3|. is positioned between the screen 3| and the plates 50-50 to back up the screen 3| and prevent the material from forcing it into the apertures provided in the strainer plates 50-50 and thereby burst the screen. The screen 30 also has a coarse mesh and is positioned between the screen 3| and the end of the stock screw i5.

Having selected the screens 30, 3| and 32 of the desired mesh and having mounted the rolls thereof on the shafts 31-31, the ends of the three screens are aligned with each other, and are passed through the slot 21 and around the roller 36 so that they engage the shoulder 25 and the groove 26 of the support 24. The screens are pushed along the shoulder and the groove until they enter the grooves 23-23 provided in the rectangular flange l3 of the head l0. The screens are drawn across the opening l8 until the ends thereof ride against the shoulder 40 and in the groove 4| provided in the support 35. The screens then pass around the roller 4i and through the slot 42 provided in the support 33 to the takeup shaft 44 rotatably mounted in the supports 45-45. It should be noted that to assemble the screens across the opening I8 in this manner, it is first necessary to energize the motor ll and permit it to drive the shafts 51 and 64 so as to position the splined cams 10-10 opposite to that shown in Fig. 6 so that the ends of the yok'es 53 and 54-54 will be positioned their maximum distance away from the grooves 23-23.

Having assembled the screens 30, 3| and 32 across the opening Is in this manner, a perforated plate 50 is positioned in the support 24 so that the flange 5|. formed on the bottom end of the plate engages the groove 26, while the flange 5| formed on the top of the plate rides against the shoulder 25 of the support and then slid manually from the support 24 into position B across the opening l8 of the head i0, in which position it covers one-half the opening IS. A second perforated plate 50 is then positioned in the support 24 in the above-described manner and slid manually to the left until it occupies position B across the opening I8, and in so doing it pushes the first plate 50 into position A across the opening II.

The plates are positioned across the opening |3 of the head |0 so that the right and left ends thereof extend slightly beyond the end yokes 54-54 and the joint between the plates falls directly beneath the pad 55 provided on the central yoke 53. Since there is no material 52 in the head l0, it is a relatively simple matter for the operator of the apparatus to manually assemble the screens and plates in the above-described manner so that they are properly aligned with respect to the opening l3, the central yoke 53 and the yokes 54-54.

After positioning the plates across the opening l8, the motor 31 is then energized to rotate the shafts 5'! and 64 one-half turn which places each of the cams IO-I0 in the position shown in Fig. 6. When the cam 10 operating within each of the toggle links 55-55 is in this position, the toggle links have drawn their respective yokes inwardly to urge the perforated plates 50-50 toward the screens 33, 3| and 32. This movement of the plates serves to compress the screens 33, 3| and 32 together and against the edges of the strips 20-23 positioned around the flange i3. The narrow edges of the strips 20-23 causes a screens and the opening l3.

when the yokes are in this position, the means for driving the stock screw may be energized to, rotate the screw to force the compound 52 to be strained from the cylinder l4 into the straining head M. The stock screwwill eventually force the compound 52 to be strained from the cylinder ll into the head I and thence through the screens 30, 3| and 32 and the perforated plates "-50. The strained material emerging from the perforations in the plates will fall directly upon the plates 15-15 and from there onto the conveyor I05, which-serves to convey the strained material to the particular apparatus in which it is to be used or processed.

when the apparatus is operating in this manner, the screen 3|, which has been described as the fine mesh straining screen, collects all the unmixed particles and the foreign matter of the compound 52, which are of such size that they will not pass through the fine meshes of the screen 3|. As the stock screw l5 continues to operate, the screen 3| gradually clogs-up with these oversize particles of the material 52, whereupon the pressure required to strain the compound 52 through the screen 3| increases greatly and likewise the temperature of the material 52 within the head l0 increases.

As the screen 3| clogs up it retards the flow of the compound 52 therethrough and the backing up of the material against the screen compresses the screens tightly together so that the fine mesh screen 3| becomes interlocked with the coarse mesh screens 30 and 32. In addition to this fact, the pressure built up in the material 52 which is required to force it through the screen 3| under these conditions becomes so great that portions of the screen lying over the openings in the plates 50-50 are forced partially into the openings, that is, slight dents in the screens occur at each of the openings in the plates, which dents serve to interlock the screens together and to the plates 50-50. a

When the pressure and temperature of the material 52 being strained reach a predetermined point, it is an indication that the screen 3| is so clogged up that further straining therewith is unsafe, and the screens 30, 3| and 32 must be changed in order to bring fresh areas of the screens and backing up plates*50-50 into position across the-opening l8. When such condie tions occur, rotation of the stock screw I5 is terminated and the motor 81 is energized to rotate the shafts 51 and 64 one-half revolution which simultaneously urges the yoke 53 and the yokes 54-50 away from the plates 50-50. This movement of the yokes provides the maximum clearance between the ends of the yokes and the plates.

Assuming that the piston 95 (Figs. 1 and 2) and the ram 91 are positioned at the right end of their stroke, a third perforated plate 50, like the plates "-50 occupying A and B positions across the opening I8, is positioned in the support 24 in the manner described hereinabove. The valve I02 is operated to admit the hydraulic fluid into the cylinder 30 so that the piston 95 will drive the ram 91 to the left into engagement with the third perforated plate 50. At the same time that the control valve I02 is operated to cause the piston l 10 to move in this direction, the torque motor 41 connected to the takeup shaft 44 to which the screens 30, 3| and 32 are connected is energized and exerts a substantial pull on the screens. The ram :1 moves to the left and slides all three plates "-50 and the screens 30, 3| and 32 along their own plane as a. unit until the third plate 50 assumes the B position across'the opening l3. In so doing, the first plate 50 is now positioned in the support 33 and the portion of the clogged screens withdrawn from the opening l3 therewith are taken up by the shaft 44 driven by the torque motor 41. In this manner fresh areas of the screens are positioned across the opening I! contiguous with the third plate 50. The torque motor 41 must develop suflicient torque to separate the screens from each plate as it is advanced past the slot 42 with the plate by the cylinder 30. Since the material 52 in the strainer head I0 is embedded in the meshes of the screens, it is necessary for thecylinder 30 to exert suflicient lateral force on the plates and screens to cause the screen 30 to sever the compound '52 in the opening II from that embedded within itsmeshes.

The control valve I32 is then operated to admit the hydraulic fluid to the cylinder 90 to return the ram 01 to the right end of its stroke, and a fourth perforated plate like the plates "-50 is positioned in the support 24 in the above-described manner. After the plate has been positioned in the support, the control valve I02 is again operated to cause the piston 35 and the ram 31 thereby to be advanced to the left thereby sliding the second, third and fourth plates and the screens as a unit across the opening l0 until. the fourth plate occupies the B position across the opening l0. The first and second plates "-50 are now positioned in the support 39 and the portions of the screens withdrawn from the opening with the last insertion of the fourth plate thereacross is taken up by the torque motor 41.

It will be noted that as the plates 50-50 are pushed into the support 39 with the screens, the motor separates the screens from the plates as it takes them up on the shaft 44. This permits the first and second plates so discharged from the opening I 8 to be used in the same manner to eject the third and fourth plates when it becomes necessary to again draw fresh areas of the screens across the opening 8.

Due to the interlocking effect produced'by the material embedded in the meshes of the screens and in the perforations of the plates and the physical interlocking of the screens with each other and with the perforations of the plate, the plates and the screens move across the opening l0 as a unit when the ram 31 is actuated by the cylinder 00.

As pointed hereinabove, the screen 3| is a fine mesh screen, which performs the straining operation on the compound 52. That is, the screen 3| limits the size of the particles of foreign matter and agglomerates permissible in the strained compound. The screen 32 is as a coarse mesh screen, which backs up the unsupported area of the screen 3| to prevent material from bursting the screen 3| as it is forced therethrough. The screen 30 is positioned between the end of the stock screw l5 and the fine screen 3| for the purpose of carrying oil all of the matter collected in the meshes of the screen 3| when the screens are changed.

70 When the stock screw is operating as described.

thematerial 52 passes freely through the coarse mesh screen 30 and impinges against the fine straining screen II, whereupon the particles in the material that are too large for passage therethrough collect on the surface of the screen 3| as the material is forced therethrough. All the matter collected on the screen 3| lies in between the meshes of the coarse screen 30 (Fig. 5). When the screens are changed in the abovedescribed manner, the movement of the screen 3| with the screens and plates severs the compound embedded within the meshes thereof from the mass of compound positioned adjacent to the surface thereof, and carries the compound embedded therein out of the head I I. Since the oversize particles of the material are mixed in with the material embedded within the meshes of the coarse screen ll, they are carried out of the head when the screens are changed. In this way none of the matter collected on the screen II will be dragged across the surface of the compound at the end of the stock screw and therefore will not be left in the strainer head.

It is believed to be apparent from the above description that the screen acts as a scavenger screen by making certain that all the agglomerates and foreign matter of the material I2 which would not pass through the fine mesh screen ii is removed from the strainer head It. In this way longer periods of operation of the apparatus may be obtained, because if some of the compound which would not pass through the screen were left in the strainer head when the screens are changed, this material would immediately clog up the fresh area of the screen II drawn across the opening It and thereby shorten the time the apparatus could be operated before the screens must be changed again.

What is claimed is:

1. In an apparatus for straining materials including an elongated cylinder having a stock screw therein for advancing a material to be strained, the improvement which comprises a plurality of mils of wire mesh screen rotatably mounted so that the screens may be withdrawn from their respective rolls and positioned across the end of the cylinder to strain over-sized particles from material advanced by the stock screw, means provided on the end of the cylinder for supporting that portion of the screens positioned across the end of the cylinder, a perforated plate slidably positioned in said supporting means of the cylinder to back up the screens as the materlal is forced therethrough by the stock screw, means for selectively clampin the perforated plate tightly against the supporting means to support the plate and the screens against the pressure of the material being forced through the screens, means provided on the supporting means for sliding the plate and screens laterally across the supporting means of the cylinder to advance fresh portions of the screens from their rspective rolls and another backing up plate across the end of the cylinder, and means for coiling up the used screens as they are withdrawn from the end of the cylinder.

2. In an apparatus for straining materials including an elongated cylinderhaving a stock screw therein for advancing a material to be strained, the improvement which comprises a straining head mounted on the end of the cylinder and having a bore therethrough for receiving the end of the stock screw and the material conveyed thereby, a plurality of rolls of belt-like screens rotatably mounted so that the screens may 'be slidably positioned across the open end of the straining head to strain the oversized particles from the material being conveyed through the straining head by the stock screw, a perforated plate slidably positioned across the open end of the straining head to back up the screens as the material is forced therethrough, means for holding the plate across the opening of the screening head, said holding means adapted to selectively urge the plate and the screens tightly against the end of the straining head to support the plate against the pressure of the material being strained and to release the plates so that the belt-like screens and perforated plate may be slidably withdrawn across the opening of the straining head, fluid pressure power means mounted on the straining head for pushing the plates and the clogged up screens supported thereby as a unit laterally across the end of the straining head so as to draw fresh portions of the belt-like screens and backing plates across said opening, means provided on the straining head for supporting the used backing up plate after the previously used plate and screens have been pushed beyond the opening of the straining head, and'a motor driven means for exerting suflicient pull on the screens to separate the screens from the backing up plates and coil them up as the screens and plates are withdrawn from the opening by the fluid pressure means.

3. In an apparatus for straining materials including an elongated cylinder having a stock screw therein for advancing a material to be strained, the improvement which comprises a straining head mounted on the end of the cylinder and having a bore therethrough for receiving the end of the stock screw and the material conveyed thereby, a plurality of rolls of wire mesh screens rotatably mounted so that the screens may be drawn across the open end of the straining head, said screens comprise a coarse mesh screen contiguous with the mass of material conveyed by the screw, a fine mesh screen contiguous with said coarse screen to strain oversized particles and lumps of material conveyed by the stock screw and a coarse mesh screen contiguous with the fine screen, a perforated plate slidably positioned across the open end of the straining head and contiguous with the last-mentioned coarse screen. said perforated plate serving to support the screens as the material is forced through the fine mesh screen, said last-mentioned coarse mesh screen serving to prevent the material being strained from rupturing the fine mesh screen at the apertures provided in the perforated plate, means for selectively clamping the plate and screens tightly against the end of the straining head to support the plate and screens against the pressure developed in the material as it is forced through the fine mesh screen or release the plate and screens so that they may he slidably withdrawn from the opening in the strain- 55 ing head, fluid pressure power means provided on the straining head for sliding the plate and clogged screens supported thereby as a unit from the end of the straining head when it is necessary to position fresh portions of the screens and backing up plate across the opening of the straining head, and motor driven means for coiling up the used screens as they are withdrawn from the end of the straining head, said coiling means serving to separate the used screens from the plates, whereby the perforated plate may be used in asomi strained, the improvement which comprises a straining head secured on the end of the cylinder and having a bore therethrough for receiving the end of the stock screw and the material conveyed thereby to be strained, the open end of said straining head being rectangular in shape and having grooves provided in the horizontal sides of the opening, a plurality of rolls of wire mesh screen rotatably mounted so that the screens may be slidably positioned in the grooves in the straining head, a perforated. plate slidably positioned in the grooves for supporting the screens as the material is forced therethrough, said belt-like screens consisting of a coarse mesh screen contiguous with the mass of material to be strained, a fine mesh screen contiguous with the coarse mesh screen, a second coarse mesh screen positioned between the fine screen and the perforated plate, said fine mesh screen serving to strain agglomerated particles from the material conveyed thereto by the stock screw, said second coarse mesh screen serving to prevent the material irom forcing the fine mesh screen to the apertures of the perforated plate and thereby bursting the screen, means for supporting the perforated plate against pressure of the material being strained, means for selectively urging the supporting means tightly against the plate to press the screens tightly in the grooves provided in the straining head and for releasing the supscavenger screen in that it carries therewith all the foreign matter and oversized lumps collected on the surface of the fine mesh screen when the screens are slidably withdrawn from the straining head by said power means, whereby the foreign matter and lumps strained out of material will be completely removed from the straining head.

5. In an apparatus for straining materials including an elongated cylinder having a stock screw therein for advancing a material to be strained, the improvement which comprises a straining head secured on the end of the cylinder and having a bore therethrough for. receiving the end of the stock screw and the material conveyed thereby, said straining head having a rectangular opening at the free end thereof which is provided with a groove in the horizontal sides of said opening, a plurality of belt-like screens advanced from suitable supply roll and slidably positioned in the grooves so as to cover the rectangular opening of the straining head, at least one of said belt-like screens serving to strain agglomerated particles and foreign matter from the material, a perforated plate slidably positioned in the grooves with the screens so as to cover the rectangular opening of the straining head, said plate serving to support the screens as the material is forced therethrough by the stock screw, a plurality of yokes positioned transversely across the rectangular opening to support the plate and the screens against the pressure of material being forced through the screens by the stock screw, each of said yokes having a link support fresh movably positionedon eachend'thereof, a pair of cam shafts rotatably mounted on the rectangular end ofthe straining head, and means for rotating the cam shafts to actuate the links toward the stock screw or away from the end of the straining head as desired, whereby when the links are actuated toward the stock screw the yokes are drawn tightly against the plate so as to press the screens tightly in the grooves of the straining head and when the'links are urged away from the stock screw the yokes disengage the plate so that the plate and screens may be slidably withdrawn together from the rectangular opening of the straining head.

6. In an apparatus for straining materials 111- eluding an' elongated cylinder having a stock screw therein for advancing a material to be strained, the improvement which comprises a straining head secured on the end of the cylinder and having a bore therethrough for receiving the end of the stock screw and the material conveyed thereby, said straining head having a rectangular opening at the free end thereof which is provided with a groove on the horizontal sides of the opening. a plurality of beltlike screens advanced from suitable supply rolls andslidably positioned along their own plane in the grooves so as to cover the rectangular opening of the straining head, at least one of said screens serving to strain agglomerates and foreign matter from the material to be strained, a perforated plate slidably positioned in the grooves with the screens so as to cover the rectangularopening and support the screens as the material issforced therethrough by the stock screw, a plurality of yokes positioned transversely across the rectangular opening to support the plate against the pressure of material being forced through the screens by the stock screw, each of said yokes having a link movably positioned on 'each end thereof. a pair of cam shafts rotatably mounted on the rectangular end of the straining head, means for simultaneously rotating the cam shafts in the same direction to actuate the links toward or away from the end of the straining head as desired, whereby when the links are actuated toward the straining head the yokes are drawn tightly against the plate so as to press thescreens tightly in the grooves of the straining head and when the links are urged away from the stock screw the yokes disengage the plate so that the plate and screens may be slidably withdrawn from the rectangular opening of the straining head, and a hydraulic actuated ram mounted on the end of the strain- V ing head for sliding the perforated plate and the screens as a unit across the opening of the straining head to advance fresh portions of the belt-like screens across the opening.

'7. In an apparatus for straining materials including an elongated cylinder having a stock screw therein for advancing a material to be strained, the improvement which comprises a straining head secured on the end of the cylinder and having a bore therethrough for receiving the end of the stock screw and the material conveyed thereby, said straining head'having a rectangular opening at the free end thereof which is provided with a groove on the horizontal sides of the opening, a plurality of rolls of wire mesh screens which are rotatably mounted so that the screens may be slidably positioned in the grooves so as to cover the rectangular opening of the straining head, said screen serving to strain agglomerates and foreign matter from 1s material being faced therethrough by the screw, tionedinthegroeveswfl mwiththescreens supportthe'screensasthematerialisiorced therethrough by the stock screw, a plurality of across the rectandirection to move the links and the yokes toward or away from the end oi the straining head as desired, whereby when the links are actuated toward the straining head the yokes are drawn tightly against the plate so as to press the screens tightly in the grooves of the straining head and when the links are urged away from the stock screw the yokesvdisengage the plate so that the plate and screens may be slidably withdrawn from the rectangular opening of the straining head, a hydraulic actuated ram'mounted on the end oi the straining head for sliding the periorated plate and the screens as a unit across the opening of the straining head to advance iresh portions or the belt-like screens across the opening, and means provided on the straining head for supporting the perforated plate after it is slidably displaced irolnrthe rectangular & plate slidalbly p 1.

opening of the straining head, means for taking up the belt-like screens as they are slidably advanced across the opening of the straining head, said takeup means for the screens being positioned with respect to the straining head so as to separate the screens from the perforated plate, whereby the plate may be used again in straining operations with other portions of the belt-like screens.

- 8. In an apparatus for straining materials including an elongated cylinder having a stock screw therein for advancing a material to be strained, the improvementwhich comprises a having a rcctangularopening in the free end 50 thereof and a groove provided in each horisontal side oi said opening, a plurality of belt- 18 liheseree'ns advaneediromsuitablesupplyrolla and slidably positioned along their ownplane in the grooves so as to'overlap the rectangular opening of the straining head, at least one of said screens serving tostrainagglomeratesand ioreign matter from the material, means for properlysupportingthescreenrollsatoneend oi the opening in line with'said grooveameans positioned at the other end of the opening for taking up the screens, a plurality of perforated plates slidably positioned in said grooves eon tiguous with said screenssoas to supportthe screenswhenthematerlalisbeingioreedtherevthroughhrythestockscresur, means providedat the screen receiving end of the opening for sup,- porting the perforated plates so they may he slid across the rectangular opening, a hydraulic 0perate'dramslidablymountedontheplatemp-.

porting means for sliding the plates and the sereens'rlrom the rectangular'opening as a wit to advance rresh portions of the belt-like screens across the opening of the straining head, a plus rality of yokes for supporting the plates against the pressure or the material being forced the screens, means for actuating the yoke cause themtopress theplates andthescreens the opening.

JOSEPH E. LODGE.

nnrnnnivcss crrnn The following references are of record in the file of this patent:

UNITED s'rs'rns PATENTS Date Number Name 642,813 Cowen Feb. 6, 1800 642,814 Cowen Feb. 6, 1900 1,195,578 Garrahan Aug. 22, 1918 1,762,367 Vandergriit June 10, 1280 1,931,872 Lodge Oct. 24, 1233 2,037,823 Royle Apr. 21, 1928 2,384,148 Yaeger Sept. 4, 1945 

